Angiostatin was identified by scientists at Harvard Children's Hospital, under a Sponsored Research Agreement funded by EntreMed, as the endogenous antiangiogenic factor responsible for the phenomenon of suppression of tumor growth by tumor mass. The systemic suppression of metastatic tumor growth was caused by a 38 kD circulating angiogenesis inhibitor isolated from urine of primary tumor-bearing mice. The sequence of this molecule bears sequence homology to an internal fragment of plasminogen of both mouse and man, and a corresponding fragment of human plasminogen has similar inhibitory activity in vitro and in vivo. Murine and human cDNAs encoding the angiogenesis inhibitor were cloned by the PI in EntreMed laboratories.The specific aim of this proposal is to determine the best recombinant system for production and expression of biologically active human angiostatin. When the most efficient process is identified, a Phase II proposal will address issues related to large-scale production and purification of this naturally-occurring cancer therapeutic. The long term goal is to provide sufficient angiostatin in purified active form to conduct preclinical studies and clinical safety and efficacy tests in man. In this Phase I proposal, we will 1) maximize expression of human recombinant angiostatin in Escherichia coli and determine its biological activity, 2) explore the use of the methylotropic yeast, Pichia pastoris, as a system for producing large quantities of glycosylated angiostatin, 3) assess and compare the quality and biological activity of the angiostatin produced by recombinant techniques in each system (eukaryotic and prokaryotic). The commercial potential for angiostatin as a therapeutic for inhibition of metastatic tumor growth is enormous. PROPOSED COMMERCIAL APPLICATION: Malignant neoplasms are responsible for more than 0.5 million deaths annually and 22.5% of all deaths in the U. S. (Cresanta, 1992). Annually, over one million Americans are diagnosed with cancer and will require effective therapy. Angiostatin, could be used therapeutically for angiogenesis-dependent metastatic neoplastic diseases such as breast, prostate, lung, solid tumors and leukemia. Angiostatin may also have therapeutic potential for other angiogenesis-related diseases, such as hemangioma, diabetic retinopathy, macular degeneration, psoriasis, and Kaposi's sarcoma.